ISSN: 2338-1345 – Vol. 8 1&2 (2020) 1-14 Journal online https://ojs.bakrie.ac.id/index.php/APJSAFE

Asia Pacific Journal of Sustainable Agriculture Food and Energy (APJSAFE)

Biological Studies on the Natural Enemies in Suppression of Coconut Stick , Graeffea crouanii (Le Guillou) in Fiji

Deesh, Aradhana D.1*, Joshi, Ravindra C.1,2, Jokhan, Anjeela D.3, Khan, Mohammed M. G.3 and Jerard, B. Augustine4

1Koronivia Research Station, Ministry of Agriculture, Nausori, Fiji 2CAB International South-East Asia, Malaysia; SAFE-Network, Indonesia 3Faculty of Science, Technology and Environment, The University of the South Pacific, Suva, Fiji 4 ICAR-CIARI, Port Blair-744105, Andaman and Nicobar Islands, India

*Corresponding author: [email protected]

Abstract — Coconut stick insect, Graeffea crouanii (Le Guillou) is one of the important pests of coconut palms in Fiji. It causes extensive leaf damage resulting in production losses. The field surveys revealed the presence of several naturally-occurring natural enemies (predators and parasitoids) on G. crouanii in the major coconut growing regions in the Fiji Islands viz., Viti Levu, Vanua Levu and Taveuni. Two species of egg parasitoids, Paranastatus verticalis Eady and Paranastatus nigriscutellatus Eady were recorded as the most prevalent natural enemies, of which P. verticalis was the dominant species. This paper presents information from field and laboratory studies on the pest and dominant natural enemy and role of P. verticalis on the population suppression of G. crouanii in Fiji. The release of P. verticalis and field sanitation were the two best management practices identified that contributed to the improvement of plant health toward the management of G. crouanii.

Keywords — Cocos nucifera L., Coconut stick insect pest, Graeffea crouanii, natural enemies, Paranastatus verticalis, Fiji.

tourism industry by way of beautifying the beaches. INTRODUCTION Coconuts and copra (the dried meat of the coconut) Coconut palm, Cocos nucifera L., is widely regarded are important agricultural products that are widely as “The Tree of Life” due to the use of all its parts in used and exported from Fiji. supporting livelihood supporting in the South Pacific. The coconut palms provide environment The coconut plantations are affected by various services, support food security and livelihood of categories of plant pests in different growing most people in the South Pacific region. Besides, regions, and a few of them are fatal to the palms. the food, nutrition, and income securities, C. Child (1974) has reported 751 species of as nucifera is also considered as more important pests of coconuts around the world. In Fiji, the component for the tourism industry in the South coconut stick insect, Graeffea crouanii (Le Guillou) Pacific Islands Countries and Territories (Luigi, is one of the principal insect pests causing severe 2005). In Fiji, the coconut palm is one of the most losses to the coconut industry (Deesh et al. 2020). economically important crops occupying the coastal They cause severe defoliation resulting in crop areas supporting livelihood in terms of providing losses, and even death of trees. Knowledge on the food, fuel and shelter, and adding value to the natural enemies is of paramount importance towards

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ISSN: 2338-1345 – Vol. 8 1&2 (2020) 1-14 Journal online https://ojs.bakrie.ac.id/index.php/APJSAFE the development of ecologically sustainable Laboratory Evaluation of Natural Enemies integrated pest management approach against this Observations on natural enemies made during chronic pest in coconut plantations. the field surveys were further tested in the laboratory This paper provides information from the field and conditions to ascertain the stages of G. crouanii that laboratory studies on the diversity of the naturally- were vulnerable to natural enemies. The freshly laid occurring natural enemies, their spatial and temporal eggs, nymphs and adults of G. crouanii were population dynamics, biology and role of the exposed to these different natural enemies identified dominant egg parasitoid, Paranastatus verticalis and collected during field samplings in Vanua Levu Eady, on the population suppression of G. crouanii (Dawara), Viti Levu (Namaumada), and Taveuni in Fiji. It also provides guidance on the practical (Salialevu), Fiji (Figure 2). This was undertaken to integration of IPM options against G. crouanii for determine the most dominant and effective smallholders. indigenous natural enemies of the G. crouanii. The collected specimens of G. crouanii and mass reared MATERIALS AND METHODS egg parasitoids were preserved in 70% ethanol for geometric analysis and species identification. The Field Survey of Natural Enemies species determination was conducted by the Unitec Field surveys for natural enemies of the coconut Institute of Technology, New Zealand. stick insect, Graeffea crouanii (Le Guillou) were carried out in the major coconut growing areas of Egg Parasitoids and their Population Dynamics three main islands of Fiji group viz., Viti Levu, To study the parasitism level in field, five coconut Vanua Levu and Taveuni (Figure 1). The survey palms were randomly selected at each of the was confined to the wet zones of the major coconut hotspots for the sampling of G. crouanii eggs. In plantations since preliminary studies between 2009 this sampling technique, the litter was collected from -2012 on pest status showed that the pest was palm crown (area between the axial of the coconut localized mostly in wet areas compared to dry zone, leaves) and base area (around the palm base) to where the incidence was lower (Deesh et al., 2013). understand the spatial and temporal population The geo-positional coordinates of the surveyed area dynamics of egg parasitoids in the fields. The eggs lay between 17.4057(S), 178.2454(E) & 18.1641(S), of G. crouanii were separated from the debris and 177.4559(E) for Viti Levu; 16.8595(S), 178.8621(E) kept in labeled Petri dishes. These eggs were & 16.6284(S), 179.8677(E) for Vanua Levu; and observed at the laboratory and kept at room 16.8115(S), 179.8650(E) & 16.9925(S), temperature ranging 180.4717(E) for Taveuni (Deesh, 2018).

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ISSN: 2338-1345 – Vol. 8 1&2 (2020) 1-14 Journal online https://ojs.bakrie.ac.id/index.php/APJSAFE

Figure 1. Location of the field surveys sites for the coconut stick insect, G. crouanii and its natural enemies in Fiji (Viti Levu, Vanua Levu and Taveuni). (Source: Polynesian Cultural Centre, www.polynesia.com).

Figure 2. Location of the sampling sites (hotspots) for the coconut stick insect, G. crouanii natural enemies in Vanua Levu (Dawara), Viti Levu (Namaumada) and Taveuni (Salialevu), Fiji. significant difference in the average percentage The parasitoids that emerged were used for parasitism found in G. crouanii eggs retrieved from identification and detailed life-table studies. The palm crown and around base area were analyzed

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ISSN: 2338-1345 – Vol. 8 1&2 (2020) 1-14 Journal online https://ojs.bakrie.ac.id/index.php/APJSAFE using the Independent Two-sample t-test in SPSS environment with three methods: (i) sticking the (Allen and Kellie, 2010). eggs on leaf, (ii) eggs placed at the base of palms, and (iii) eggs hanged at the crown area of palms. Biology of the Egg Parasitoids on G. crouanii Field releases of egg parasitoids, Paranastatus Elucidating the biology of G. crouanii is crucial spp. were made in G. crouanii infested coconut for evaluating the efficacy of the natural enemies plantations in Salialevu, Taveuni Island to evaluate under laboratory conditions. Various conditions of their impacts on G. crouanii. Releases of culturing G. crouanii was undertaken and the Paranastatus spp. were made in two kinds of observations made on the biology of G. crouanii coconut plantations, namely coconut plantations reared in the laboratory conditions are in without field sanitation/intercropping, and coconut conformation with O’Connor et al. (1954). Detailed plantation with field sanitation/intercropping. biological studies were carried out in the laboratory on the egg parasitoids, Paranastatus spp. using the RESULTS AND DISCUSSIONS host eggs of G. crouanii. The emergence periodicity, Field Survey of Natural Enemies oviposition and longevity of Paranastatus spp. were observed over a period of During the field surveys, several kinds of natural one year using the eggs of G. crouanii reared in the enemies were observed with different functional cages, and eggs collected from the fields. feeding guilds. General predators like Indian myna (Acridotheres tristis), chicken (Gallus gallus After 48 hours of exposure of fresh eggs of G. domesticus), spiders, lizards, cattle and ants were crouanii to Paranastatus spp., the eggs were encountered feeding on eggs, nymphs, and adults of isolated from each other. The eggs were kept in G. crouanii in coconut plantations. Their abundance individually labelled Petri dishes to determine the varied across sites and sampling dates. The incubation time for parasitoids, number of adult populations of lizards and ants were highest parasitoids emerged per egg and their sex ratio. This followed by A. tristis and spiders, while the cattle was conducted to investigate if there were any and G. domesticus were very low (Table 1). Similar patterns of periodicity in adult emergence as well as observations on predation by G. domesticus were patterns in the sex ratio of the egg parasitoids reported from Tokelau Island (Dharmaraju, 1978), emerging from parasitised eggs. The measurement where they were found picking up the eggs of G. (length and width) of G. crouanii individual egg was crouanii under coconut and pandanus canopies. recorded using the graduated eye piece stage However, in Western Samoa, Fiji and some other microscope, while the weight was measured using countries G. domesticus consumed the nymphs and an analytical balance, respectively. The male and adults of G. crouanii that fell on ground when palms female adult parasitoids that emerged were fronds were burnt beneath the palm on a still day identified through visual observation of its size, (Lever 1946; Lever 1947). G. domesticus managed presence or absence of ovipositor, and using the to find all eggs on bare soil, whereas the eggs taxonomic keys (Eady, 1956). escaped predation in grassy areas. However, in our field surveys, the G. domesticus and cattle Field Evaluation of the Egg Parasitoids populations ranged from not present to few where Field experiment was conducted during 2012- the severe infestation of G. crouanii was also 2013 to evaluate the efficacy of biological control recorded (Deesh and Swamy, 2012). They observed agents against G. crouanii on coconut at the that the eggs of G. crouanii were damaged by the Agricultural Research Station in Koronivia, cattle stamping eggs and nymphs in areas where Nausori. The parasitism was recorded at three cattle were allowed to graze. Hence, recommended different parts of the coconut plant (underneath the establishing free range poultry and controlled leaves, the leaf axial area and at the base of palms) grazing of cattle in coconut plantations as one of the at ten different sites, for assessment of natural ecofriendly strategies to contain the G. crouanii enemies which are either air-borne (found on the infestations. palm) or soil-borne (found around palm base). The Eggs of G. crouanii consumed by several fresh eggs of G. crouanii from the cages were predatory ant species, Pheidole megacephala and exposed in fields to monitor the prevalence of the Tapinoma melanocephalum in Fiji and Tonga (O’ biological control wasps (parasitoids) in the natural Connor, 1949; Bedford, 1976; Bedford, 1978;

ISSN: 2338-1345 – Vol. 8 1&2 (2020) 1-14 Journal online https://ojs.bakrie.ac.id/index.php/APJSAFE

Crooker, 1979 and Singh, 1979), Solenopsis approaches to enhance their populations and geminata (Crooker, 1979) (Mariau, 2001), and predatory actions. In future more research is needed Pheidole caldwelli (Singh, 1972) have been on the influence of habitat manipulation and natural reported. In Fiji, Singh (1977, 1979 & 1981) enemy and pest interactions. obtained up to 76% of predation, and highlighted Two species of parasitoids belonging to the major role of predators in controlling the stick Order Hymenoptera under Family Eupelmidae and insect. In Australia, eggs and young nymphs of the Genus Paranastatus were recorded from the eggs of Phasmid Dydimuria were found in the nests of G. crouanii that were collected from palm crown Iridomyrmex spp. (Readshaw, 1965). Dharmaraju and palm basal areas in three selected hotspots in (1978) observed the blue-tailed skink lizard (also Vanua Levu, Viti Levu and Taveuni Islands. The referred to as western skink), commonly found on two egg parasitoids species were Paranastatus palm groves and the vicinity of building, predating verticalis Eady and Paranastatus nigriscutellatus on the eggs of G. crouanii. Eady (Lal, 2009), of which P. verticalis was the Though we have good information on the most dominant species. These parasitoids were diversity of predators on G. crouanii developmental described earlier by Eady (1956). In Fiji, Singh stages in Fiji and across the infested Pacific Islands (1977, 1979 & 1981) has reported 0% to 11% Countries, we currently lack data on their impacts on parasitization by P. verticalis, while the G. crouanii population regulation, and also on parasitization by P. nigriscutellatus was close to nil.

ISSN: 2338-1345 – Vol. 8 1&2 (2020) 1-14 Journal online https://ojs.bakrie.ac.id/index.php/APJSAFE Table 1. Predator diversity and abundance on or near coconut palms, at three hot-spots of coconut stick insect, G. crouanii, in Vanua Levu (Dawara), Viti Levu (Namaumada) and Taveuni (Salialevu), during November 2012- September 2013, Fiji.

Survey Sites Abundance of Predators Island (Site) Month & Indian Myna Chicken Spiders Lizards Cattle Ants Year Acridotheres tristis L. Gallus gallus domesticus (L.)

Vanua Levu Nov. 2012 + – ++ ++ – ++ (Dawara) Jan. 2013 + + ++ + + ++ Mar. 2013 + – + + – ++ May 2013 ++ + ++ + – + July 2013 + + + ++ – ++ Sept. 2013 ++ – ++ ++ + +

Viti Levu Nov. 2012 ++ + + ++ + ++ (Namaumada) Jan. 2013 + – + ++ – ++ Mar. 2013 + – ++ ++ – ++ May 2013 + + + ++ + + July 2013 + + + + – ++ Sept. 2013 ++ – + + – +

Taveuni Nov. 2012 ++ + ++ ++ + ++ (Salialevu) Jan. 2013 ++ + + ++ + + Mar. 2013 ++ – + + + ++ May 2013 + – + ++ + ++ July 2013 + + ++ ++ + ++ Sept. 2013 ++ – + + + ++

Foot Notes: – Not present + Few numbers ++ Moderate numbers +++ Large numbers Scale for Birds & Chicken: – Not present + Few (0-10) ++ Moderate (11-20) +++ Large (21-30) Scale for Spiders & Lizards: – Not present + Few (0-20) ++ Moderate (21-30) +++ Large (31-40) Scale for Cattle: – Not present + Few (0-15) ++ Moderate (16-25) +++ Large (26-50) Scale for Ants: – Not present + Few (0-50) ++ Moderate (51-100) +++ Large (101-150)

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Laboratory Evaluation of Natural Enemies The natural enemies (predators and parasitoids) encountered during the field surveys, had varied preferences to G. crouanii growth stages exposed. For the egg parasitoids, their only preference was eggs of G. crouanii, while for the predators all the stages were attacked, but preference differed among the predator species (Table 2).

Table 2. Laboratory evaluation to determine parasitism/ predation by natural enemies on different stages of G. crouanii.

Natural Enemies Stages of G. crouanii Egg Nymph Adult Male Adult F emale Parasitoids Paranastatus verticalis Eady √ x x x Paranastatus nigriscutellatus Eady

Predators Indian myna (Acridotheres tristis) x √ √ √ Poultry/Chicken (Gallus gallus √ x √ √ domesticus) Spiders x √ x x Lizards √ √ x x Cattle √ x x x Ants x √ √ √

Foot Notes: √ - with parasitism/predation; x- without parasitism/predation.

parasitoids may be delayed or prevented depending Egg Parasitoids and their Population Dynamics on conditions that are affecting the emergence of The number of G. crouanii eggs retrieved from eggs. In Taveuni in 1963, less than 10% parasitism the crown area were less, as compared to the base of was obtained by Paine (1968). In Tonga, Crooker the canopy (Table 3). Interestingly, the percent egg (1979) reported that P. nigriscutellatus was parasitism was slightly lower for eggs retrieved from responsible for killing 30% to 40% of the G. the palm base area, compared to those retrieved from crouanii eggs. the crown area. Our results are in line with the findings of the earlier researchers (O’Connor et al. Biology of the G. crouanii and Egg Parasitoids 1954; Stechmann, 1985). In the present study, the incubation period of G. Among the two Paranastatus species, the crouanii egg was recorded to be 64 to 153 days for percent parasitism recorded from the eggs retrieved nymph emergence (Table 4), at room temperature from both the crown and/or base of palm in all the ranging from 24°C to 28°C with a relative humidity sampling sites, showed that P. verticalis always had varying from 65 to 70%. Fully grown female nymph higher percent of eggs parasitized, as compared to P. had six nymphal stages and measured from 80 to 90 nigriscutellatus (Table 3). The percent eggs mm long and from 3 to 4 mm broad. Total parasitized from the crown area by P. verticalis were development period of female nymph ranged from 19.2, 18.8 and 10.9, and the average number of eggs 105 to 112 days with a mean of 108.5 days. Male G. parasitized from the base of the palm were 16.7, crouanii had five nymphal stages and its 18.0, and 14.1, in Vanua Levu (Dawara), Viti Levu development was completed in 95 to 102 days with (Namaumada) and Taveuni (Salialevu), respectively a mean of 98.5 days. Males had a pair of wings, and (Table 3 & Figure 3). The egg parasitism ranges a pair of antennae at the anterior end of the body reported by earlier researchers for the two species of measured from 75-80 mm in length and 2-3 mm in Paranastatus are either similar and /or slightly width. The findings of this study on the number of higher to those recorded by us. O’Conner et al. nymphal instars for male and female of G. crouanii (1954) in Taveuni and Vanua Levu, recorded are in conformation with the studies of O’Connor et parasitism ranging from less than 10% to as high as al. (1954) and Taleaua (1980). 52%. He further noticed that the emergence of the

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Table 3. Egg parasitoids emergence from eggs of the coconut stick insect, G. crouanii collected from the crown area and palm base area in Vanua Levu (Dawara), Viti Levu (Namaumada) and Taveuni (Salialevu), during November 2012- September 2013, Fiji.

Crown Area Base Area P. verticalis P. nigriscutellatus P. verticalis P. nigriscutellatus Survey Sites Island Sampling Total No. No. of % No. of % Total No. No. of % No. of % (Site) Time of Eggs Eggs Parasitism Eggs Parasitism of Eggs Eggs Parasitism Eggs Parasitism (Month & Retrieved Parasitised Parasitised Retrieved Parasitised Parasitised Year) Vanua Levu Nov. 2012 8 1 12.5 0 0 13 1 7.7 2 15.4 (Dawara) Jan. 2013 6 2 33.3 0 0 15 4 26.7 1 6.7 Mar. 2013 10 1 10 1 10 14 4 28.6 1 7.1 May 2013 11 2 18.1 1 9 17 1 5.9 1 5.9 July 2013 8 1 12.5 0 0 22 4 18.1 1 4.5 Sept. 2013 7 3 28.5 0 0 15 2 13.3 2 13.3 Average 19.2 3.2 16.7 8.8

Viti Levu Nov. 2012 6 2 33.3 1 16.7 9 2 22.2 0 0 (Namaumada) Jan. 2013 8 1 12.5 1 12.5 14 3 21.4 1 7.1 Mar. 2013 8 1 12.5 0 0 13 2 15.4 2 15.4 May 2013 7 1 14.3 0 0 11 1 9.1 0 0 July 2013 4 0 0 1 25 23 4 17.4 2 8.7 Sept. 2013 5 2 40 0 0 9 2 22.2 0 0 Average 18.8 9.0 18.0 5.2

Taveuni Nov. 2012 9 1 11.1 1 11.1 17 3 17.6 1 5.9 (Salialevu) Jan. 2013 10 2 20 1 10 16 2 12.5 2 12.5 Mar. 2013 14 2 2 1 7.1 20 3 15 1 5.5 May 2013 9 2 2 0 0 19 3 15.8 1 5.3 July 2013 10 2 20 1 10 17 2 11.8 1 5.9 Sept. 2013 10 1 10 1 10 17 2 11.8 1 5.9 Average 10.9 8.0 14.1 6.8

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Figure 3. Percent egg parasitism by egg parasitoids, Paranastatus verticalis and Paranastatus nigriscutellatus from the coconut stick insect, G. crouanii eggs collected from crown and base area of palms in Vanua Levu (Dawara), Viti Levu (Namaumada) and Taveuni (Salialevu), Fiji.

Table 4. Biology of G. crouanii observed under laboratory conditions, Koronivia, Nausori, Fiji.

Time of Av. Days Av. Length of Av. Width of Egg Av. Weight of No. of Nymphs Emergence for Nymphs Egg (mm) (mm) Egg (g) /Egg Emergence

May 2013 153 4.06 1.94 0.46 1 June 2013 99 4.12 1.95 0.46 1 July 2013 151 4.09 1.96 0.46 1 Aug. 2013 91 4.09 1.95 0.46 1 Sept. 2013 98 4.08 1.95 0.46 1 Oct. 2013 97 4.08 1.95 0.46 1 Nov. 2013 64 4.09 1.96 0.45 1 Dec. 2013 89 4.08 1.95 0.45 1 Jan. 2014 86 4.08 1.96 0.45 1 Feb. 2014 96 4.08 1.95 0.45 1 Mar. 2014 91 4.09 1.95 0.45 1 Apr. 2014 90 4.07 1.95 0.46 1 Range 64 -153 4.06 - 4.12 1.94 -1.96 0.45 – 0.46 1 Mean ± S. D. 100 ± 25.78 4.08 ± 0.01 1.95 ± 0.01 0.46 ± 0.01 -

S. D.: Standard Deviation. crouanii mostly brown in color and development Fully grown female nymphs are light was completed in 95 to 102 days with brown/greenish in color and measured from 80 to 90 mm long and from 3 to 4 mm broad. Total a mean of 98.5 days. Similar findings on biology of development period of female nymph ranged from G. crouanii was made by Clausen (1978) and 105 to 112 days with a mean of 108.5 days. Male G. O’Connor et al. (1954). Paine (1968) who reported that the period from hatching to emergence of the

8 ISSN: 2338-1345 – Vol. 8 1&2 (2020) 1-14 Journal online https://ojs.bakrie.ac.id/index.php/APJSAFE adult female is 15 to 16 weeks, and in males 13.5 to oviposition significantly varied with the age of the 14.5 weeks. The adult female have two pairs of small parasitoids. The highest oviposition was found in the movable wings, but cannot fly. About 3 weeks after one-day old parasitoids (av. 13.4 eggs per female per becoming an adult, the female adult started laying day) and it was 33.33% of the total egg exposed in eggs, up to 130 beings produced in their lifetime, this study (Table 6). This is in conformity with study which may last up to 18 weeks. Males are able to fly, of Perera and Hemachandra (2014) who reported and may survive up to 25 weeks. Mating was also that one-day-old parasitoid laid more eggs per observed whereby the male climbed on the back of female with 56.05% of total fecundity. The number female and stayed in that position until actual mating of eggs parasitised on second and third days was commenced. When ready for mating, the adult male 8.48 and 5.00, respectively which represented moved slightly down from usual position to properly 26.67% and 13.33% of the total fecundity. pass its abdomen down and around one side of the The male adults of Paranastatus spp. life span female’s abdomen to insert the aedeagus. Even were significantly shorter than the female adults though the male was carried around by the female (Figure 5). Male average longevity was 4.24 days, from place to place in this position, the attached while female survived on an average of 5 days. The male was observed feeding independently. The longevity is an important character of adult number of eggs laid by a female G. crouanii varied parasitoids, that has effect on oviposition and slightly with the host on which it was reared. eventually the overall production of mass culture Development of two species of Paranastatus in (Lee and Heimpel, 2005). This biological the laboratory by rearing on the freshly laid eggs of information is vital to mass rear Paranastatus spp. G. crouanii revealed that the eggs hatch in 18 to 135 for field releases in the IPM program of G. crouanii. days (Table 5). Similar observations were made by O’Connor et al. (1954) who found the incubation Field Evaluation of the Egg Parasitoids, period ranging from 50 to 68 days. Their study also Paranastatus spp. suggested possibility that under certain conditions, G. crouanii eggs exposed around different emergence of the parasitoids may be delayed or positions of the coconut palm tree to the natural prevented. The data of the present study has higher enemies showed that for eggs pasted underneath the range since data was gathered over a period of one coconut leaves, and those pasted on small pieces of year as compared to similar study by O’Connor et coconut leaves hung around the crown area had al. (1954) whose data was for period of two months. 80.89% and 90.62% egg retrieval, respectively, From the laboratory study on the rearing of compared to the eggs placed in Petri dish around the Paranastatus of the total of 6,782 adult egg palm base (Table 7). The percentage of G. crouanii parasitoids 1,060 were male and 5,722 were female nymphs hatched and percentage of egg parasitism by parasitoids. There were more adult females than the parasitoids were similar for eggs pasted underneath males of Paranastatus, with the sex ratio of 1 male the leaves or pasted on pieces of leaves hung around to 5.2 females (Table 5). Present findings are in the palm crown. The exposed eggs of the G. crouanii conformation with the studies of O’Connor et al. had equal opportunity for parasitism by the natural (1954), who reported greater preponderance of the enemies presents around the eggs in both situations. females Paranastatus spp. from the G. crouanii eggs In Tonga, while assessing the role of natural enemies collected in axils of fronds of coconut palms and on in the field, Rapp (1995) also reported that the P. the ground on islands of Taveuni and Vanua Levu. verticalis emerged from less than 1% of all the eggs In the current study, the development of pest G. recovered. crouanii egg and two species of egg parasitoids, Field releases of egg parasitoids, Paranastatus Paranastatus spp. reared on its host (eggs of G. spp. in two kinds of coconut plantations, namely crouanii) revealed that the time taken for egg coconut plantations without field parasitoids development was shorter than that of the sanitation/intercropping, and coconut plantation host. Paranastatus spp. with its high proportion of with field sanitation/intercropping resulted in slight females and a developmental period much shorter reduction of G. crouanii infestations in field without than that of its host, might be expected to exert field sanitation/intercropping, as compared to field efficient control of the stick insect as reported by with sanitation/intercropping (Figure 6). O’Connor et al. (1954). Paranastatus spp. laid eggs for 1- 3 days, but it decreased over the days (Figure 4). The rate of

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Table 5. Biology of Paranastatus spp. on coconut stick insect, G. crouanii eggs, under laboratory conditions, Koronivia, Nausori, Fiji.

No. of Adult Parasitoids Sex Ratio Time of Emergence of Av. Length of Av. Width of Av. Weight of Total No. of Emerged by Sex (Male: Female) Emergence Parasitoids Egg (mm) Egg (mm) Egg (g) Parasitoids Male Female Male Female (Av. Days) Emerged Parasitoids Parasitoids Parasitoid Parasitoid

May 2013 135 4.06 1.94 0.46 12 2 10 1 5 June 2013 52 4.12 1.95 0.46 12 2 11 1 5.5 July 2013 128 4.09 1.96 0.46 12 2 10 1 5 Aug. 2013 61 4.09 1.95 0.46 12 2 10 1 5 Sept. 2013 65 4.08 1.95 0.46 12 2 10 1 5 Oct. 2013 72 4.08 1.95 0.46 12 2 10 1 5 Nov. 2013 18 4.09 1.96 0.45 14 2 12 1 6 Dec. 2013 86 4.08 1.95 0.45 11 2 9 1 4.5 Jan. 2014 55 4.08 1.96 0.45 12 2 10 1 5 Feb. 2014 49 4.08 1.95 0.45 13 2 11 1 5.5 Mar. 2014 48 4.09 1.95 0.45 14 2 12 1 6 Apr. 2014 50 4.07 1.95 0.46 12 2 10 1 5 Range 18 -135 4.06 - 4.12 1.94 -1.96 0.45 - 0.46 11-13 2 9-12 1 4.5-6 Mean ± S.D. 68 ± 33.70 4.08 ± 0.01 1.95 ± 0.01 0.46 ± 0.01 12.33 ± 0.89 - 10.42 ± 0.90 - 5.21 ± 0.45

Av. data from one-year laboratory study. S.D.: Standard Deviation.

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Figure 4. Relationship between the egg parasitism by two species of Paranastatus across the number of days under laboratory conditions, Koronivia, Nausori, Fiji, 2014.

Table 6. Longevity period of Paranastatus spp. and percent parasitism under laboratory conditions, Koronivia, Nausori, Fiji, 2014.

Details of Emergence No. of the Oviposition Parasitoids Period Egg 1 (Mean ± S. D.) Egg 2 (Mean ± S. D.) Egg 3 (Mean ± S. D.) [Days] Male Female Male Female Male Female Parasitoid Parasitoid Parasitoid Parasitoid Parasitoid Parasitoid

Individual 2.2 1.6 11.8 1.08 7.36 0.64 4.36 Mean

Total Mean 13.4 ± 2.98 8.48 ± 4.82 5 ± 6.5 ± S. D.

Parasitism (%) 33.33 26.67 13.33

S.D.: Standard Deviation. together with the use of naturally-occurring egg G. crouanii eggs are sensitive to high temperatures. parasitoids, Paranastatus spp. is suggested for In plantation with low ground cover, eggs probably ecological sustainable management of G. crouanii become desiccated by the sun, while the high under infestations in Fiji. growth of plantations with poor weed management provided shade cover for the eggs developing on the CONCLUSIONS ground. This assumption is supported by literature: Crooker (1979) and Lever (1969) mention high pest During the field surveys, several naturally-occurring densities in plantations with dense ground cover in biological control agents on coconut stick insect, Tonga. Singh (1981) reported that plantations with Graeffea crouanii (Le Guillou) were found. low ground cover were free from infestation in Fiji. Predators noticed were Indian myna (Acridotheres In Fiji, Singh (1977, 1979, 1981) found a 12% to tristis), chicken (Gallus gallus domesticus), spiders, 44% increase in desiccated eggs in plantation with lizards, cattle and ants. Among the predators, the low ground cover when compared to areas under lizards and ants were highest in numbers. The only poor weed management. Thus, integration of parasitoids encountered attacking eggs of G. cultural methods such as sanitation/intercropping, crouanii were identified as Paranastatus verticalis Eady and Paranastatus nigriscutellatus Eady, and

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Table 7. Field exposure and retrieval of laboratory reared G. crouanii eggs from the different positions of the coconut palm.

Egg Exposure % Eggs % Eggs not % No. % No. Nymph % Parasitism Retrieved Retrieved Emergence Hatched by Parasitoids (Mean ± S.D.) (Mean ± S.D.) from Egg (Mean ± S.D.) (Mean ± S.D.) (Mean ± S.D.)

Eggs glued 80.89 ± 13.39 19.11 ± 13.39 12.82 ± 7.56 53.26 ± 14.42 14.81 ± 8.97 underneath leaves Eggs placed at 61.70 ± 17.79 38.30 ± 17.79 11.16 ± 5.01 38.11 ± 12.32 12.43 ± 9.00 palm base Eggs hung 90.62 ± 7.62 9.38 ± 7.62 19.37 ± 9.65 55.74 ± 9.76 15.51 ± 7.00 around palm crown

S.D.: Standard Deviation.

Figure 6. Impact of release of two species of egg parasitoids, Paranastatus spp. on the G. crouanii infestations in two kinds of coconut plantations, Salialevu, Taveuni Island, Fiji.

biological studies on the Paranastatus spp. revealed they were the most dominant one and present in all vital information on their sex ratio, duration to adult coconut plantations surveyed. P. verticalis always stage, relation between fecundity and age of the had the higher percent of G. crouanii eggs adult female, life span of adult males and females, parasitized, as compared to P. nigriscutellatus in all optimum host-parasite ratio, and other life history coconut plantations surveyed G. crouanii. parameters were necessary to standardize mass Information on the life cycle of G. crouanii under rearing techniques for Paranastatus spp., and which laboratory conditions facilitated in the development can be used in future to manage G. crouanii of the mass rearing techniques of egg parasitoids, P. infestations. More ecological engineering research is verticalis and P. nigriscutellatus. This was crucial needed in future across various agroecological zones for evaluating the efficacy of the natural enemies in Fiji, where the integration of cultural and under laboratory and field conditions. The series of 12

ISSN: 2338-1345 – Vol. 8 1&2 (2020) 1-14 Journal online https://ojs.bakrie.ac.id/index.php/APJSAFE biological methods are fine-tuned for the selected islands of Fiji. Fiji Agricultural development of the integrated pest management Journal 53 (1): 18-24. package against G. crouanii in Fiji Islands. Deesh, A.D., Jokhan, A.D., Joshi, R.C., Khan M.G.M. and Jerard, B.A. 2020. Seasonal ACKNOWLEDGEMENT abundance and host plants of coconut stick The senior author (A.D. Deesh) thank the insect (Graeffea crouanii Le Guillou) in University of the South Pacific (USP), Suva Fiji for coconut plantations of Fiji Islands. Journal of the research grant, to the Unitec Institute of Plantation Crops 48 (1): 1-10. Technology, New Zealand for species identification https://updatepublishing.com/journal/index.p of the egg parasitoids, and to the Ministry of hp/JPC/article/view/6211 Agriculture, Fiji for providing resources and expertise. Dharmaraju, E. 1978. Coconut Pest Control in the Tokelau Islands. Alafua Agricultural Bulletin REFERENCES 3: 9-12.

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